A centrifugal separtor for non-cohesive particulates, such as are found in transmission oils and hydraulic liquids, rather than the cohesive combustion products found within internal combustion engine lubricants, consists of a housing enclosing a vertical spindle on which spins a liquid reaction driven rotor container. The container is divided internally by inwardly extending partition wall into separate outflow chambers. Non-cohesive particulates which separate from the liquid, and are held against the peripheral side wall by centrigual force during rotation, slump therefrom in the absence of rotation and risk forming a slurry that gets carried to the outflow chamber. An upwardly extending, outwardly inclined barrier wall forms a contaminant retention region with a restricted neck defined by the separation of the barrier wall edge from the side wall, that permits deposits on the barrier wall to carry to the peripheral side wall and spread across it during rotation, and does not interfere with slumping absent rotation and inhibits the slumped material from being washed into the outflow before rotation recommences.